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<FONT color="green">001</FONT>    /*<a name="line.1"></a>
<FONT color="green">002</FONT>     * Licensed to the Apache Software Foundation (ASF) under one or more<a name="line.2"></a>
<FONT color="green">003</FONT>     * contributor license agreements.  See the NOTICE file distributed with<a name="line.3"></a>
<FONT color="green">004</FONT>     * this work for additional information regarding copyright ownership.<a name="line.4"></a>
<FONT color="green">005</FONT>     * The ASF licenses this file to You under the Apache License, Version 2.0<a name="line.5"></a>
<FONT color="green">006</FONT>     * (the "License"); you may not use this file except in compliance with<a name="line.6"></a>
<FONT color="green">007</FONT>     * the License.  You may obtain a copy of the License at<a name="line.7"></a>
<FONT color="green">008</FONT>     *<a name="line.8"></a>
<FONT color="green">009</FONT>     *     http://www.apache.org/licenses/LICENSE-2.0<a name="line.9"></a>
<FONT color="green">010</FONT>     *<a name="line.10"></a>
<FONT color="green">011</FONT>     * Unless required by applicable law or agreed to in writing, software<a name="line.11"></a>
<FONT color="green">012</FONT>     * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.12"></a>
<FONT color="green">013</FONT>     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.13"></a>
<FONT color="green">014</FONT>     * See the License for the specific language governing permissions and<a name="line.14"></a>
<FONT color="green">015</FONT>     * limitations under the License.<a name="line.15"></a>
<FONT color="green">016</FONT>     */<a name="line.16"></a>
<FONT color="green">017</FONT>    package org.apache.commons.configuration.tree;<a name="line.17"></a>
<FONT color="green">018</FONT>    <a name="line.18"></a>
<FONT color="green">019</FONT>    import java.util.Collections;<a name="line.19"></a>
<FONT color="green">020</FONT>    import java.util.HashSet;<a name="line.20"></a>
<FONT color="green">021</FONT>    import java.util.Set;<a name="line.21"></a>
<FONT color="green">022</FONT>    <a name="line.22"></a>
<FONT color="green">023</FONT>    /**<a name="line.23"></a>
<FONT color="green">024</FONT>     * &lt;p&gt;<a name="line.24"></a>
<FONT color="green">025</FONT>     * A base class for node combiner implementations.<a name="line.25"></a>
<FONT color="green">026</FONT>     * &lt;/p&gt;<a name="line.26"></a>
<FONT color="green">027</FONT>     * &lt;p&gt;<a name="line.27"></a>
<FONT color="green">028</FONT>     * A &lt;em&gt;node combiner&lt;/em&gt; is an object that knows how two hierarchical node<a name="line.28"></a>
<FONT color="green">029</FONT>     * structures can be combined into a single one. Of course, there are many<a name="line.29"></a>
<FONT color="green">030</FONT>     * possible ways of implementing such a combination, e.g. constructing a union,<a name="line.30"></a>
<FONT color="green">031</FONT>     * an intersection, or an "override" structure (were nodes in the first<a name="line.31"></a>
<FONT color="green">032</FONT>     * hierarchy take precedence over nodes in the second hierarchy). This abstract<a name="line.32"></a>
<FONT color="green">033</FONT>     * base class only provides some helper methods and defines the common interface<a name="line.33"></a>
<FONT color="green">034</FONT>     * for node combiners. Concrete sub classes will implement the diverse<a name="line.34"></a>
<FONT color="green">035</FONT>     * combination algorithms.<a name="line.35"></a>
<FONT color="green">036</FONT>     * &lt;/p&gt;<a name="line.36"></a>
<FONT color="green">037</FONT>     * &lt;p&gt;<a name="line.37"></a>
<FONT color="green">038</FONT>     * For some concrete combiner implementations it is important to distinguish<a name="line.38"></a>
<FONT color="green">039</FONT>     * whether a node is a single node or whether it belongs to a list structure.<a name="line.39"></a>
<FONT color="green">040</FONT>     * Alone from the input structures, the combiner will not always be able to make<a name="line.40"></a>
<FONT color="green">041</FONT>     * this decision. So sometimes it may be necessary for the developer to<a name="line.41"></a>
<FONT color="green">042</FONT>     * configure the combiner and tell it, which nodes should be treated as list<a name="line.42"></a>
<FONT color="green">043</FONT>     * nodes. For this purpose the {@code addListNode()} method exists. It<a name="line.43"></a>
<FONT color="green">044</FONT>     * can be passed the name of a node, which should be considered a list node.<a name="line.44"></a>
<FONT color="green">045</FONT>     * &lt;/p&gt;<a name="line.45"></a>
<FONT color="green">046</FONT>     *<a name="line.46"></a>
<FONT color="green">047</FONT>     * @author &lt;a<a name="line.47"></a>
<FONT color="green">048</FONT>     * href="http://commons.apache.org/configuration/team-list.html"&gt;Commons<a name="line.48"></a>
<FONT color="green">049</FONT>     * Configuration team&lt;/a&gt;<a name="line.49"></a>
<FONT color="green">050</FONT>     * @version $Id: NodeCombiner.java 1206476 2011-11-26 16:19:53Z oheger $<a name="line.50"></a>
<FONT color="green">051</FONT>     * @since 1.3<a name="line.51"></a>
<FONT color="green">052</FONT>     */<a name="line.52"></a>
<FONT color="green">053</FONT>    public abstract class NodeCombiner<a name="line.53"></a>
<FONT color="green">054</FONT>    {<a name="line.54"></a>
<FONT color="green">055</FONT>        /** Stores a list with node names that are known to be list nodes. */<a name="line.55"></a>
<FONT color="green">056</FONT>        protected Set&lt;String&gt; listNodes;<a name="line.56"></a>
<FONT color="green">057</FONT>    <a name="line.57"></a>
<FONT color="green">058</FONT>        /**<a name="line.58"></a>
<FONT color="green">059</FONT>         * Creates a new instance of {@code NodeCombiner}.<a name="line.59"></a>
<FONT color="green">060</FONT>         */<a name="line.60"></a>
<FONT color="green">061</FONT>        public NodeCombiner()<a name="line.61"></a>
<FONT color="green">062</FONT>        {<a name="line.62"></a>
<FONT color="green">063</FONT>            listNodes = new HashSet&lt;String&gt;();<a name="line.63"></a>
<FONT color="green">064</FONT>        }<a name="line.64"></a>
<FONT color="green">065</FONT>    <a name="line.65"></a>
<FONT color="green">066</FONT>        /**<a name="line.66"></a>
<FONT color="green">067</FONT>         * Adds the name of a node to the list of known list nodes. This means that<a name="line.67"></a>
<FONT color="green">068</FONT>         * nodes with this name will never be combined.<a name="line.68"></a>
<FONT color="green">069</FONT>         *<a name="line.69"></a>
<FONT color="green">070</FONT>         * @param nodeName the name to be added<a name="line.70"></a>
<FONT color="green">071</FONT>         */<a name="line.71"></a>
<FONT color="green">072</FONT>        public void addListNode(String nodeName)<a name="line.72"></a>
<FONT color="green">073</FONT>        {<a name="line.73"></a>
<FONT color="green">074</FONT>            listNodes.add(nodeName);<a name="line.74"></a>
<FONT color="green">075</FONT>        }<a name="line.75"></a>
<FONT color="green">076</FONT>    <a name="line.76"></a>
<FONT color="green">077</FONT>        /**<a name="line.77"></a>
<FONT color="green">078</FONT>         * Returns a set with the names of nodes that are known to be list nodes.<a name="line.78"></a>
<FONT color="green">079</FONT>         *<a name="line.79"></a>
<FONT color="green">080</FONT>         * @return a set with the names of list nodes<a name="line.80"></a>
<FONT color="green">081</FONT>         */<a name="line.81"></a>
<FONT color="green">082</FONT>        public Set&lt;String&gt; getListNodes()<a name="line.82"></a>
<FONT color="green">083</FONT>        {<a name="line.83"></a>
<FONT color="green">084</FONT>            return Collections.unmodifiableSet(listNodes);<a name="line.84"></a>
<FONT color="green">085</FONT>        }<a name="line.85"></a>
<FONT color="green">086</FONT>    <a name="line.86"></a>
<FONT color="green">087</FONT>        /**<a name="line.87"></a>
<FONT color="green">088</FONT>         * Checks if a node is a list node. This implementation tests if the given<a name="line.88"></a>
<FONT color="green">089</FONT>         * node name is contained in the set of known list nodes. Derived classes<a name="line.89"></a>
<FONT color="green">090</FONT>         * which use different criteria may overload this method.<a name="line.90"></a>
<FONT color="green">091</FONT>         *<a name="line.91"></a>
<FONT color="green">092</FONT>         * @param node the node to be tested<a name="line.92"></a>
<FONT color="green">093</FONT>         * @return a flag whether this is a list node<a name="line.93"></a>
<FONT color="green">094</FONT>         */<a name="line.94"></a>
<FONT color="green">095</FONT>        public boolean isListNode(ConfigurationNode node)<a name="line.95"></a>
<FONT color="green">096</FONT>        {<a name="line.96"></a>
<FONT color="green">097</FONT>            return listNodes.contains(node.getName());<a name="line.97"></a>
<FONT color="green">098</FONT>        }<a name="line.98"></a>
<FONT color="green">099</FONT>    <a name="line.99"></a>
<FONT color="green">100</FONT>        /**<a name="line.100"></a>
<FONT color="green">101</FONT>         * Combines the hierarchies represented by the given root nodes. This method<a name="line.101"></a>
<FONT color="green">102</FONT>         * must be defined in concrete sub classes with the implementation of a<a name="line.102"></a>
<FONT color="green">103</FONT>         * specific combination algorithm.<a name="line.103"></a>
<FONT color="green">104</FONT>         *<a name="line.104"></a>
<FONT color="green">105</FONT>         * @param node1 the first root node<a name="line.105"></a>
<FONT color="green">106</FONT>         * @param node2 the second root node<a name="line.106"></a>
<FONT color="green">107</FONT>         * @return the resulting combined node structure<a name="line.107"></a>
<FONT color="green">108</FONT>         */<a name="line.108"></a>
<FONT color="green">109</FONT>        public abstract ConfigurationNode combine(ConfigurationNode node1,<a name="line.109"></a>
<FONT color="green">110</FONT>                ConfigurationNode node2);<a name="line.110"></a>
<FONT color="green">111</FONT>    <a name="line.111"></a>
<FONT color="green">112</FONT>        /**<a name="line.112"></a>
<FONT color="green">113</FONT>         * Creates a new view node. This method will be called whenever a new view<a name="line.113"></a>
<FONT color="green">114</FONT>         * node is to be created. It can be overridden to create special view nodes.<a name="line.114"></a>
<FONT color="green">115</FONT>         * This base implementation returns a new instance of<a name="line.115"></a>
<FONT color="green">116</FONT>         * {@link ViewNode}.<a name="line.116"></a>
<FONT color="green">117</FONT>         *<a name="line.117"></a>
<FONT color="green">118</FONT>         * @return the new view node<a name="line.118"></a>
<FONT color="green">119</FONT>         */<a name="line.119"></a>
<FONT color="green">120</FONT>        protected ViewNode createViewNode()<a name="line.120"></a>
<FONT color="green">121</FONT>        {<a name="line.121"></a>
<FONT color="green">122</FONT>            return new ViewNode();<a name="line.122"></a>
<FONT color="green">123</FONT>        }<a name="line.123"></a>
<FONT color="green">124</FONT>    }<a name="line.124"></a>




























































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